Page Faults occurs when a program requests an address on a page that is not in the current set of memory resident pages.
When a page fault is encountered, the program execution stops and is set to the Wait state. The operating system searches for the requested address on the disk. When the page is found, the operating system copies it from the disk into a free RAM page. The operating system allows the program to continue with the execution afterward.
Monitoring Page Faults/sec counter shows both had and soft page faults, so it can be difficult to determine whether the page faults value indicates performance problems in SQL Server, and should be addressed, or presents a normal state.
There is no specific Page Faults/sec value that indicates performance problems. Monitoring Page Faults/Sec should provide enough information to create a baseline that will be used to determine normal server performance. The value depends on the type and amount of memory, and the speed of disk access. A sustained or increasing value for Page Faults/sec can indicate insufficient memory.